THE SOLAR SYSTEM By: Tyler, Alyssa, Brad

VOCABULARY Solar system- System of nine planets including earth and objects that revolve around the sun.

I CAN STATEMENTS I can compare models of the solar system I can Explain that gravity holds planets in orbits around the sun

IDEAS ABOUT THE SOLAR SYSTEM Early observers noted the changing positions of the planets and developed ideas about the solar system based on their observations and beliefs. People know that the suns gravity holds the solar system together Just as earths gravity holds the moon in its orbit around the earth.

EARTH-CENTERED MODEL Many early Greek scientists thought the planets the sun and the moon were fixed in separate spheres that rotated around earth. The stars were thought to be in another sphere that also rotated around earth.

SUN-CENTERED MODEL Copernicus stated that the moon revolved around earth and that earth and the other planets revolved around the sun. Using his telescope Galileo observed that Venus went through a full cycle of phases through the moon. He also observed that the apparent diameter of Venus was smallest when the phase was near full.

MODERN VIEW OF THE SOLAR SYSTEM We know that the solar system is made up of nine planets including earth and many smaller objects that orbit the sun. The solar system includes a huge volume of space that stretches in all directions from the sun.

HOW THE SOLAR SYSTEM FORMED The solar system formed from part of a nebula of gas ice and dust. A nearby star might have exploded or nearby O- or B- type stars formed.

PLANET FORMATION Not all the nearby gas, ice and dust was drawn into the core of a cloud fragment. The inner planets of the solar system Mercury, Venus, Earth, and mars are small rocky planets with iron cores.

MOTIONS OF THE PLANETS When Nicholas Copernicus developed his sun-centered model of the solar system he thought that the planets orbited the sun in circles. Kepler also discovered that the planets travel at different speeds in their orbits around the sun.

SUMMARY The planets in the solar system revolve around the sun The suns immense gravity holds the planets in their orbits The solar system formed from a piece of a nebula of gas, ice, and dust As the piece of nebula contracted nuclear fusion beganat its center and the sun was born The p-lanets orbits are elliptical Planets that are closer to the sun revolve faster than those that are farther away from the sun